Electron gun



April 3, 1956 c. P. MAJKRzAK ELECTRON GUN Filed Nov. l.

INVENTOR CHA RLES MJKRZAK ATTORNEY therein.

United States Patent 11 Claims." (Cl. 313-82) This inventionrelatestoelectron gunsfand more particularly to the mechanicalstructure'and assembly of the electron gun.

The basic,.prblem found 1iny 4prior Varrangements of electron guns is`thatof holding can accurate alignment,

both axialand spaced, of anumber of insulated elec-` trodes ofparticular shapes.

Having inmind this basic problem, it isan object of my invention toprovide a construction of electron vguns that lendsitself to accuracyandv toease of fabrication and assembly.

Another object of my invention is .to provide in the electron gunconstruction and arrangement Vthaticreates self-alignment for both theaccelerating electrode subassembly and the cathode sub-assembly withoutan undue amount of jigging.

Still a further object of my invention is to provide a means of joiningthe two sub-assemblies into a nal'assembly that will require a minimumof skill .to obtain accuracy and a production line quantity output.

The .above-mentioned` and other features `and objects of this inventionand the manner of 'attaining them will be best understood by reference`tothe following description of embodimentsof this invention takeninconjunction with the accompanying drawings, wherein:

Fig. ll is a longitudinal cross-section viewof an electron gun inaccordancewith the principles of this invention;

Fig. 2 is a traverse Vcross-section yview along line 2--2 on Fig. l;

Fig; 3 is a longitudinal cross-section view of an elec tron gun showinga modified form of the invention;

Fig. 4 is a traverse cross-section view taken along line 4--4 in Fig. 3;and

Fig. 5 is an exploded view in cross-section of a detail in Fig. V3. r

Referring'to Figs. l and 2 ofthe drawing, one of the embodiments of myinvention is shown which allows for accurate alignment of parts withoutan undue amount of jigging and expensive machinery. The ease of assemblyis achieved by the fact that the electronV gun is constructed in twomain sections, namely-the cathode section and the racceleratingelectrode section. lThe cathode section has a housing member 1cylindrical in shape with an inwardly extending flange 2. Theaccelerating electrode section also has a housing member 3 cylindricalin shape with an inwardly extending flange or shoulder 4, but hav-14 inga smaller cross-section than that 'of housingl member 1.

ln assemblingthe cathode section, it is lirst desired to malte acathodeV sub-assembly by inserting a ceramic washer'S into a smallmetallic cylinder 6 through which the lament .leads 7 are brought `bymeans of aperturesv These leads are connected to the filament coil S bymeans of soldering, brazing, or any other suitable method. ConcentricWith this arrangement isthen placed n a cathode element 9 which is spotwelded orebrazed to cylinder 6 suchthat one of the ilamentleads 7 iswelded or brazed at the same time to the interior of cylinder 6, such asat point 10. The cathode element 9 has its .25, 28, and 30 is receivedsnugly therein.

2,740,913 Patented .Apta "3, Vv'11556 thermionic emitting surfacelocated on a nipple, hereafter referredtozas the emittingV surface 11.Thissub=assembly .is `nextpositioned inandwelded or otherwise secured toVan annular. .shell 12.

A focusing electrode 14 in cupshape issecured to a ceramic washer15,'and a lead 16 is connected thereto. The ceramic washer 15 issandwiched between llange 2 and an annular element 17- spot welded orbrazed .to

. housing member 1.

. VTo complete .the-assembly of thecathode section. a section ceramicwasher18 having a larger interior-difarneter. than ceramic-washer l15 issandwiched between theaelement17 andV aliange 19 .of a ring 20 welded orbrazed towhousing member 1. This sandwiching is accomplished in suchamanner that -the annularange '13 Yof shell 12 isfgrippetibetweenceramic washers V15 and .1S to hold the cathode element in properalignment with aperture y21 located in `ceramic washer 15. The focusingelectrodelead 16 is brought out through aperture 22 in ,theannularshell12, the lead 16 being protected against .shorting `by ceramic .sleeve23. A small amount of jigging is required to properly align cathodeelement 9 and its accompanying emitting surface 11 when the annularflangel 13 is being -sandwiched between ceramic washers 15 and 18.

Stillreferring to Figs. l and 2 the electrode assembly -containedtinhousing 3 will'now be described. lNozzleshaped tip 24 is spot welded orbrazed to a third accelerat inglelectrode 25and then slipped intohousing member 3 on top of a ceramic-spacer 26. Following this isceramic `spacer'27, a.second accelerating electrode 28, another ceramicspacer 29,y followed by a first accelerating electrode 30 to which isspot welded or brazed a metallic focusing disc 31.

The electrodes 25, 28, and 30 are of sheet stockeither stamped, punched,Vor turned. Each electrode hasa `in'thehousing member 3, while theinterior dimension is such that the smaller end liange 33 of theelectrodes It shouldalso be noted thatthe outer dimension of ceramicspacers 26,

l2'7., ,und'29 is larger than the dimension of electrodelateral flange34. Therefore, the snug lit of the ceramic spacers 26, 27, and 29against housing member 3 plus the snug fit of the end flanges 33 ofelectrodes 25, 28, and 3tl, in ceramic spacers26, 27, and-29 hold saidelectrodes fin proper `axial and spaced alignment.

inthe process of inserting electrodes 25 and 28 in housing member 3,small stiff lead wires 35 and 35a are secured, as by spot welding, tothe lateral projections'of the electrodes prior to inserting nextelement. Each lead wire is brought out of housing member 3 through auinsulator 42. Y

To accomplish a completed assembly a stepped cylinder 36 having aninwardly extending flange 37 is used. Y

The smaller end of the cylinder 36 is telescoped into housing member 3,such that flange 37 is ilush against the projection 34 where it is spotwelded to member 3 to hold vfirmly the electrodes 25, 28, and 30 indesired alignment.

vHousing member 1 is then received in the larger end ofthe steppedcylinder 36 care being taken to line up apertures 38 in the treadportion of stepped cylinder 36 with apertures 39in ceramic Vwashers 15and '18. Houslingmember lfisthen placed against Athetread portion ofsembly leads 41 and 41a are disposed through apertures 38 and 39, andfrom there to lead wires 35 and 35a.

Figs. 3, 4, and illustrate another form of this invention wherein thesame reference characters are employed for identical parts as describedin the foregoing embodiment.

In this embodiment cathode housing member 43 comprises a cylindricalshell having an inwardly extending tiange 44 that contains apertures 45for leads 41 and 41a. Resting upon the flange 44 is a sheet of mica 48containing two series of apertures 49 and 5f), also a central aperture51 to expose emitting surface 11, and openings for alignment withopenings 45 for passage of leads 41 and 41a. Annular shell 46 of thecathode assembly is secured in position by nipples 52 contained in anannular ring 53 extending through apertures 49 and spot welded. Afocusing electrode 54 is held concentric to emitting surface 11 by anannular disc 55 containing nipples 56 which protrude through apertures50 to which the electrode is secured by spot welds.

Housing member 3 and the ceramic spacers for the accelerating electrodesare identical to those used in the first embodiment. However, the thirdaccelerating electrode 57 is a solid screw machine part shaped as shownin drawing. The second accelerating electrode 58 is similar to thesecond accelerating electrode 28 in Fig. 1 except that it is a screwmachine part. The ceramic spacers 26, 27, and 29 and acceleratingelectrodes 57 and 58 are disposed in alternate manner and provided withthe connections 35 and 35a.

First accelerating electrode 59 is a screw machine part that is providedwith a reduced interior dimension 60 for concentrating the electronbeam. The lateral fiange projection 61 is recessed to receive flange 37to which it is welded. This unit is then telescoped with housing member3, aligning apertures 38 with lead wires 35 and 35a and pressure appliedprior to spot welding or brazing which then holds electrodes 57, 58, and59 in spaced and axial alignment.

The housing member 43 is inserted into the larger end of steppedcylinder 36 and apertures 38, 62, and 45 are aligned. When thisalignment is completed pressure is applied and the units are joined byspot welding or brazing. The pressure produced by the flange 44 andtread portion of stepped cylinder 36 clamps the mica sheet 48 in place,thereby providing the proper alignment between cathode element 9 and theaccelerating electrodes 57, 5S, and 59.

The focusing electrode potential is applied through lead i6, while thefirst accelerating electrode, 30 in the first embodiment and 49 in thesecond embodiment, is at ground potential through the stepped cylinder36. Potentials of progressively higher values are applied throughelectrode leads 41, 35 and 41a, 35a to the second and third acceleratingelectrodes, respectively.

Although I have shown and described certain specific embodiments of myinvention, I am fully aware that many modifications thereof arepossible. Therefore, this description is made only by way of example andnot as a limitation to the scope of my invention.

I claim:

l. in an electron gun, a cathode assembly comprising a cathode, acylindrical shell, means supporting said cathode in said shell includingan insulating element in the form of a sheet having aperturestherethrough, means carried by said shell to support said element inposition crosswise thereof, an annular plate disposed on one side ofsaid insulating sheet, an annular shell to support said cathode on theother side of said sheet and means connecting said annular shell throughcertain of said apertures to said annular plate with said cathodeexposed through still another' of said apertures, a focusing electrodeclosely adjacent to said cathode and means extending through aperturesin said sheet to secure said focusing electrode thereto in concentricrelation to said cathode.

2. An electron gun comprising a first housing member, a cathode, meanssupporting said cathode in said first housing member, a second housingmember, a plurality of accelerating electrodes, means supporting saidelectrodes in alignment in said second housing member and meansconnecting together in a telescoping manner said first and secondhousing members to align said electrodes and said cathode, the meanssupporting said cathode including a sheet of insulating material havingapertures therethrough, an annular plate disposed on one side of saidinsulating sheet, an annular shell to support said cathode on the otherside of said sheet and means connecting said annular shell throughcertain of said apertures to said annular plate with said cathodeexposed through still another of said apertures.

3. An electron gun according to claim 2, further including a focusingelectrode disposed closely adjacent said cathode, and means extendingthrough apertures in said sheet to secure said focusing electrodetherethrough in concentric relation to said cathode.

4. An electron gun comprising a first housing member, a cathode, meanssupporting said cathode in said first housing member, a second housingmember, a plurality of accelerating electrodes, means supporting saidelectrdes in alignment in said second housing member, and meansconnecting together in a telescoping manner and in tandem relation saidfirst and second housing members to align said electrodes and saidcathode, said plurality of electrodes each including a lateralprojection and means supporting said electrodes in alignment includinginsulating spacers one each disposed between the projections of adjacentelectrodes and between at least one of said adjacent electrodes and thewall of said second housing member, said first housing member comprisinga shell and the means supporting said cathode including an insulatingelement and means carried by said shell to hold said element in positioncrosswise of said shell, said means carried by said shell including aninwardly extending flange, an annular element disposed laterally of saidshell, said insulating element being in sheet form sandwiched betweensaid fiange and said annular element having apertures therethrough, afocusing electrode, means extending through certain of the apertures insaid sheet to secure said focusing electrode therethrough in concentricrelation to said cathode, and means employing others of said aperturesto support said cathode.

5. An electron gun comprising a first housing member having a firstdiameter and including an inwardly protruding end portion, a cathode,means supporting said cathode axially of said first housing memberdisposed crosswise said first housing member in contiguous relation tosaid protruding end portion, a second housing member having a seconddiameter and including a shoulder portion at one end thereof, aplurality of accelerating electrodes, insulating means disposed betweenadjaf cent ones of said electrodes and between one of said electrodesand said shoulder portion for positioning said electrodes axially ofsaid second housing member, said first diameter being greater than saidsecond diameter, and a connecting member to connect together said firstand second housing members in an in line arrangement therewith, saidconnecting member including a first portion parallel to the axis of saidhousing members having an inwardly protruding end, a second portionparallel to the `axis of said housing members and a portion transverseto the axis of said housing members interconnecting said first andsecond portions, said first portion engaging the inner surface of saidsecond housing member and said second portion engaging the outer surfaceof said first housing member to align the axes of said housing membersand thereby align said electrodes with said cathode.

6. An electron gun according to claim 5, wherein the inwardly protrudingend of said first portion engages one of said electrodes to cooperatewith said insulating spacers and said shoulder portion to hold saidelectrodes in align ment with said cathode.

7. An electron gun according to claim 5, wherein said means supportingsaid cathode includes a sheet of insulating material, the transverseportion of said connecting member and the inwardly protruding endportion of said rst housing member cooperating to secure said sheet ofinsulating material in position crosswise said iirst housing member.

8. An electron gun comprising a rst housing member having an inwardlyprotruding end portion, a cathode, means supporting said cathode axiallyof said first housing member disposed crosswise said tirst housingmember in contiguous relation to said protruding end portion, a secondhousing member having a shoulder portion iat one end thereof, aplurality of accelerating electrodes, insulating means disposed betweenadjacent ones of said electrodes and between one of said electrodes andsaid shoulder portion for positioning said electrodes axially of saidsecond housing member, and a connecting member to connect together saidirst and second housing members, said connecting member including afirst portion parallel to the axis of said housing members having aninwardly protruding end, a second portion parallel to the axis of saidhousing members and a portion transverse to the axis of said housingmembers interconnecting said rst and second portions, said lirst portionengaging the inner surface of said second housing member and said secondportion engaging the outer surface of said first housing member to alignthe axis of said housing members and thereby align said electrodes withsaid cathode, said means supporting said cathode including a sheet ofinsulating material, the transverse portion of said connecting memberand the inwardly protruding end portion of said first housing membercooperating to secure said sheet of insulating material in positioncrosswise said trst housing member, said sheet of insulating materialincluding a plurality of apertures therethrough and said meanssupporting said cathode further includes an annular plate disposed onone side of said sheet of insulating material, an annular shell tosupport said cathode on the other side of said sheet and meansconnecting said annular shell through certain of said apertures to saidannular plate with said cathode exposed through still another of saidapertures.

9. An electron gun according to claim 8, further including a focusingelectrode disposed closely adjacent said cathode and means extendingthrough other apertures in said sheet to secure said focusing electro-dethereto in concentric relation to said cathode.

l0. An electron gun according to claim 5, wherein said means supportingsaid cathode includes a rst disc of insulating material having an axialaperture therethrough, a. First inwardly protruding member carried bysaid first housing member, said disc being sandwiched between said firstinwardly protruding member and said inwardly protruding end portion forpositioning thereof, a second disc of insulating material, a secondinwardly protruding member carried by said iirst housing member, aiianged cylinder with the outwardly extending flange thereof sandwichedbetween said iirst and second discs, said second inwardly protrudingmember cooperating to hold said second disc in position crosswise saidrst housing member `and means to support said cathode in said flangedcylinder in alignment with said axial aperture.

11. An electron gun according to claim 10, further including a focusingelectrode carried by said lirst disc in concentric relation with respectto said axial aperture.

References Cited in the le of this patent UNITED STATES PATENTS2,093,876 Von Ardenne Sept, 2l, 1937 2,163,740 Wales June 27, 19392,170,663 Painter Aug. 22, 1939 2,184,821 Uhlmann Dec. 26, 19392,185,807 Gabor et al Jan. 2, 1940 2,227,051 Wienecke Dec. 31, 19402,244,358 Ewald June 3, 1941 2,248,558 Schlesinger July 8, 19412,268,165 Parker et al Dec. 30, 1941 2,279,249 Roman Apr. 7, 19422,282,392 Bieling May 12, 1942 2,313,018 Krause Mar. 2, 1943 2,411,913Pierce et al. Dec. 3, 1946 2,436,265 Pohle et al. Feb. 17, 19482,441,315 Forgue May 11, 1948 2,462,921 Taylor Mar. 1, 1949 2,468,136Taylor Apr. 26, 1949 2,521,364 Haller Sept. 5, 1950 2,540,621 JohnsonFeb. 6, 1951 2,569,847 Eitel et al. Oct. 2, 1951

